The present disclosure relates to optical network technology, and more particularly to a passive optical network (PON) system in the optical access network, and a method for the master to configure the slaves in the system.
Currently there are mainly two broadband access technologies, e.g. copper cable-based access technology, such as various kinds of digital subscriber loop (DSL) technologies, and optical access technology. The access network that is implemented with optical access technology is called an optical access network (OAN).
The passive optical network (PON) is one of the commonly used technologies for implementing the OAN. The PON technology is a point-to-multipoint optical access technology, and the composition of a PON is shown in FIG. 1. The PON system comprises an optical line terminal (OLT), an optical distribution network (ODN) and an optical network unit (ONU), wherein the OLT provides a serial network interface (SNI) for the OAN to connect to one or more ODNs. The ODN is a passive optical dividing component that transports downstream data from the OLT to individual ONUs, and gathers and transports the upstream data from the ONUs to the OLT. The ONU provides the OAN with a user network interface (UNI) and connects to the ODN. An ONU that also provides user port functions, such as an Ethernet user port or a Plain Old Telephone Service (POTS) user port, is called an optical network termination (ONT).
The Gigabit PON (GPON) is one type of PON technology, the standard for which defines a configuration transfer channel called an ONU Management and Control Interface (OMCI). The OMCI channel is established between the OLT and the ONTs when the ONTs register with the OLT. The OMCI is a master-slave management protocol wherein the OLT is the master and the ONTs are the slaves. The OLT can control a plurality of ONTs that are connected to it.
In the OMCI protocol, data on the management of the ONTs by the OLT are abstracted into a protocol-independent Management Information Base (MIB). The basic information unit of the MIB is the managed entity (ME). Depending on the configurations of the ONTs, the OMCI may define that the OLT as controlling the ONTs' various MEs and the ONTs implement, under the control of the OLT, the configuration management function for various MEs.
In the prior art, MEs are created in two ways:
1. At the time the ONT is initialized or has a change in hardware, such as plugging or unplugging a board or card, the ONT determines, based on its own hardware configuration, the number of ME instances and specific attribute value for each ME, and automatically creates the ME instances. This method is associated with the hardware configuration for the ONT.
2. The OLT, based on the needed service clearance, prompts the ONT to create the ME instances through the OMCI Create message, where the number of ME instances and the specific attribute value for each ME is configured by the OLT. This method is associated with the service configuration for the ONT.
Although the ITU-T G983.2 standard defines various MEs for the ONTs managed by the OLT, the implementation class for various MEs, and the GPON protocol numbers the ME classes to facilitate configuration by the OLT, the OLT is unable to automatically know whether a particular ME is supported by an ONT before it configures the ONT because the service supported by each ONT may vary from one another. Therefore, the OLT has to send a service-relevant ME Create message to the ONTs one by one, and the OLT determines that the service is not supported if a failure is returned. This method of determining whether an ONT supports a particular ME with messaging attempts is inefficient for the OLT to communicate with the ONTs and even more so for the OLT to further control the ONTs.